Electric connecting part

ABSTRACT

It comprises an electric conduction pattern member ( 11 ) which is flexible and plate-shaped, a gel member ( 13 ) having the electric conduction pattern member embedded therein, and flexible substrate sheets ( 15   a,  15 b ) holding the gel member therebetween, the electric conduction pattern member ( 11 ) having the function of allowing the gel member ( 13 ) to be deformed and displaced by an external bending force, the stress due to the external bending force being dispersed by the gel member ( 13 ).

CROSS REFERENCE TO RELATED APPLICATIONS

Applicants claim priority under 35 U.S.C. §119 of Japanese ApplicationNo. 2003-93835 filed Mar. 31, 2003. Applicants also claim priority under35 U.S.C. §365 of PCT/JP2004/003721 filed Mar. 19, 2004. Theinternational application under PCT article 21(2) was not published inEnglish.

TECHNICAL FIELD

This invention relates to an electrical connection component forachieving electrical connection and, in particular, relates to anelectrical connection component suitable for connection at a portionsubjected to bending between a printed circuit board and a liquidcrystal display device (hereinafter referred to as an LCD) in a foldingportable telephone or at a portion subjected to bending caused bydriving.

BACKGROUND ART

Conventionally, there has been generally known a method wherein an LCDand a flexible board (flexible wiring board) mounted with, by the use ofbonding wires, an LCD driver IC for controlling driving and display ofthe LCD are electrically and mechanically connected together by bonding,with thermal pressurization, the flexible board to a terminal portion ofthe LCD by the use of heat sealing or an ACF (anti-conductive film).

There is one wherein, in order to mount a flexible board on a printedcircuit board, the flexible board is bent downward of an LCD near aconnecting portion between the LCD and the flexible board so as to befolded double, thereby mounting the flexible board between an LCD frameand the printed circuit board.

A flexible board in prior art 1 comprises an elongated base board, aplurality of wiring patterns formed on the base board, and a pluralityof reinforcing portions formed on the base board. The plurality ofreinforcing portions are disposed so as to extend in a longitudinaldirection of the base board. Part of the wiring patterns are formed atpositions offset from the respective reinforcing portions in a widthdirection of the base board.

Since a portion of the base board where the reinforcing portion isformed is more reluctant to bend than a portion where the reinforcingportion is not formed, bending stress is concentrated at the portionwhere the reinforcing portion is not formed. Part of the wiring patternsare formed at positions offset from the reinforcing portions in an axialdirection of the base board. When the base board is rolled up, sinceportions where at least part of the wiring patterns are formed arereluctant to bend due to the reinforcing portions, it is possible toprevent deformation of the wiring patterns [see, e.g. Republished PatentInternational Publication No. WO0054324 (patent document 1)].

On the other hand, in prior art 2, there is a portable telephone LCDholding structure comprising an LCD, a printed circuit board mountedwith various electrical circuits, a flexible board having an LCD drivecircuit and mounted on the printed circuit board so as to beelectrically connected thereto through the LCD and a bending portion,and a frame member holding the LCD on its upper surface and supported bythe printed circuit board, wherein assembling is made by folding thebending portion continuous with the flexible board so that the LCD, theframe member, the flexible board, and the printed circuit board aredisposed in the order named from above [see, e.g. Japanese Patent No.3110408 (patent document 2)].

Further, in prior art 3, there is a multilayer wiring board comprising aflexible bending portion, wiring layers forming the bending portion, anda flat portion having more wiring layers than the bending portion,wherein a boundary portion is provided between the flat portion and thebending portion, in which the number of wiring layers is reducedstepwise as compared with the flat portion.

In this multilayer wiring board, stress concentration is relaxed at theboundary portion between the flat portion and the bending portion of thewiring board having the bending portion, thereby preventing failure suchas breakage of the board or cutting of wiring patterns [see, e.g.Japanese Unexamined Patent Application Publication No. 2000-223835(patent document 3)].

However, in prior art 1 or 2, since a technique is adopted to improvebending resistance by performing additional processing such as shavingthinly the portion subjected to bending to increase flexibility andunifying a reinforcing plate, the additional processing is required tocause an increase in cost. Further, there is a problem that sufficientresistance cannot be obtained even by taking such a measure.

As a cause therefor, there is a problem in terms of a material such thatuse is made of copper having high conductivity as a metal for use andthe copper has a narrow elastic range and easily gives rise to stressmovement in repetitive bending.

Further, in prior art 1 or 2, there is a problem that since it isdifficult to accurately dispose wiring due to processing variation, theresistance is reduced due to subjection to stress.

Generally, a base material provided with a wiring pattern is often apolyimide resin and therefore the intrinsic problem has not been solvedthat since the polyimide resin is a hard resin having elasticity, stressconcentration is liable to occur so that the resistance is degraded dueto buckling or excessive deformation caused by bending.

Further, in prior art 3, a base material provided with the wiringpatterns is a polyimide resin and additional processing is required.

It is therefore an object of this invention to provide an electricalconnection component that can improve the bending resistance.

DISCLOSURE OF THE INVENTION

According to this invention, there is provided an electrical connectioncomponent characterized by comprising a plate-like flexible conductivepattern member, a sheet-like gel member having said conductive patternmember embedded therein, and flexible base material sheets retainingsaid gel member therebetween

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view showing a first embodiment of an electricalconnection component according to this invention.

FIG. 2 is a plan view showing, partly in section, the electricalconnection component shown in FIG. 1.

FIG. 3 is a sectional view showing, a conductive pattern member and athin film conductive layer of the electrical connection component shownin FIG. 1.

FIG. 4 is a sectional view showing a second embodiment of an electricalconnection component according to this invention.

FIG. 5 is a sectional view showing a third embodiment of an electricalconnection component according to this invention.

FIG. 6 is a sectional view showing a fourth embodiment of an electricalconnection component according to this invention.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinbelow, description will be made about a first embodiment of anelectrical connection component according to this invention. FIGS. 1 and2 show the electrical connection component in the first embodiment ofthis invention.

Referring to FIGS. 1 and 2, the electrical connection componentcomprises plate-like flexible conductive pattern members 11, asheet-like gel member 13 having the conductive pattern members 11embedded therein, and two flexible base material sheets 15 a and 15 bprovided on the front and back surfaces of the gel member 13 to retainthe gel member 13 therebetween.

Describing in further detail, the conductive pattern members 11 are eachin the form of a metal plate having a high elastic modulus and a smallthickness dimension and formed into a pattern shape. As a metal materialof the conductive pattern member 11, use is made of at least one kind ofnickel, a nickel alloy, nickel based alloys sold under the trademarkMONEL, nickel palladium, copper, phosphor bronze, and the like.

The gel member 13 is in the form of a jelly obtained by solidifyingparticles in a colloidal solution. As the gel sheet 13, a silicon oracrylic member is used. As the base material sheet 15 a, 15 b, use ismade of a resin sheet of polyimide, PET, polyester, or the like.

Further, as shown in FIG. 3, the electrical connection component in thisembodiment has at least one thin film conductive layer 17 coated on eachconductive pattern member 11. As the thin film conductive layer 17, useis made of a metal material having a conductivity higher than that ofthe conductive pattern member 11. As the metal material having theconductivity higher than that of the conductive pattern member 11, ametal plating layer, for example, is desirable.

Hereinbelow, description will be made about a method of manufacturingthe electrical connection component. At first, a metal plate having asmall thickness dimension is blanked into the belt-plate shapedconductive pattern members 11 by press working. Then, the thin filmconductive layer 17 is formed by applying metal plating to externalsurfaces of each conductive pattern member 11, thereby preparing theconductive pattern members 11 each having the thin film conductive layer17. Further, the conductive pattern members 11 each having the thin filmconductive layer 17 are embedded with respect to, as a reference, aneutral line C (see FIG. 1) bisecting the gel member 13 in a thicknessdirection thereof.

In this embodiment, each conductive pattern member 11 is embedded at aposition including the neutral line C such that the plate surfacesthereof are oriented so as to be parallel to the base material sheets 15a and 15 b. Then, the gel member 13 is, at its front and back surfaces,sandwiched between the two base material sheets 15 a and 15 b so as tobe retained, thereby obtaining the electrical connection component.

In the electrical connection component thus manufactured, although theconductive pattern members 11 are bent in response to an externalbending force, the electrical connection component has a function todeform the gel member 13 so as to displace the conductive patternmembers 11 on the neutral line C in this event and, therefore, thestress caused by the bending due to the external force is dispersed bythe gel member 13 and thus is not concentrated at the conductive patternmembers 11.

Next, the bending resistance was compared between an electricalconnection component of this invention manufactured based on the firstembodiment and a well-known FPC (flexible printed circuit).

In the electrical connection component of this invention, use was madeof conductive pattern members 11 each made of nickel and having athickness of 4 μm and the interval (pitch) of the conductive patternmembers 11 at the neutral line C was set in the range of 0.1 to 1.0 mm.A thin film conductive layer 17 was formed by plating gold onto eachconductive pattern member 11 to a thickness of 0.5 μm. As the basematerial sheet 15 a, 15 b, use was made of a polyimide resin sheethaving a thickness of 30 μm and a length of 5 cm.

With respect to the FPC compared with the electrical connectioncomponent of this invention, use was made of conductive pattern membersand base material sheets having the same sizes as those of the foregoingconductive pattern members 11 and base material sheets 15 a and 15 b. Arepetitive bending test was performed wherein the electrical connectioncomponent of this invention and the FPC were subjected to bending with adiameter of 3 mm. As a result, the resistive number of bending times ofthe FPC was 100,000 at maximum while the resistive number of bendingtimes of the electrical connection component of this invention was200,000.

FIG. 4 shows a second embodiment of an electrical connection component.In description of the second embodiment, the same symbols are assignedto portions that are the same as those of the electrical connectioncomponent described in the first embodiment, thereby omittingexplanation thereof.

In the electrical connection component of the second embodiment,conductive pattern members 11 each having a thin film conductive layer17 are disposed alternately on upper and lower sides with respect to, asa reference, a neutral line C bisecting a gel member 13 in a thicknessdirection thereof.

FIG. 5 shows a third embodiment of an electrical connection component.In description of the third embodiment, the same symbols are assigned toportions that are the same as those of the electrical connectioncomponent described in the first embodiment, thereby omittingexplanation thereof.

In the electrical connection component of the third embodiment,conductive pattern members 11 each having a thin film conductive layer17 are disposed with respect to, as a reference, a neutral line Cbisecting a gel member 13 in a thickness direction thereof so that platesurfaces of each conductive pattern member 11 are oriented obliquely ina direction to cross the neutral line C.

FIG. 6 shows a fourth embodiment of an electrical connection component.In description of the fourth embodiment, the same symbols are assignedto portions that are the same as those of the electrical connectioncomponent described in the first embodiment, thereby omittingexplanation thereof.

In the electrical connection component of the fourth embodiment, a gelmember 13 is divided into an upper gel member 13 and a lower gel member13 by a base material sheet 15 c added in a thickness direction thereof.In each of the upper and lower gel members 13, conductive patternmembers 11 each having a thin film conductive layer 17 are embedded withrespect to, as a reference, a neutral line C bisecting the correspondinggel member 13 in a thickness direction thereof so that each conductivepattern member 11 is oriented to include the corresponding neutral lineC.

The electrical connection components described in the second and thirdembodiments can be manufactured by the use of the manufacturing methodof the electrical connection component described in the firstembodiment. In each of the electrical connection components in thesecond and third embodiments, although the conductive pattern members 11are bent in response to an external bending force, the electricalconnection component has a function to deform the gel member 13 so as todisplace the conductive pattern members 11 toward the neutral line C inthis event and, therefore, the stress caused by the bending due to theexternal force is dispersed by the gel member 13 and thus is notconcentrated at the conductive pattern members 11.

It is needless to say that it is possible to change designs, dependingon the purpose of use, not only of the structures of the electricalconnection components in the first to fourth embodiments, but also ofthe materials, thickness dimensions, width dimensions, etc. of theconductive pattern members 11, the gel members 13, and the base materialsheets 15 a, 15 b, and 15 c and, further, the arrangement andorientation of the conductive pattern members 11 at the neutral line Ccan be properly performed.

As described above in terms of the embodiments, according to theelectrical connection component of this invention, the flexibleconductive pattern members are each provided on its external surfaceswith the metal thin film layer formed by metal plating and embedded inthe gel member and this gel member is protected by the base materialsheets and, therefore, the conductive pattern members can have thefunction of deforming the gel member to displace in response to bendingcaused by the external force.

Therefore, since the stress caused by the bending due to the externalforce is dispersed by the gel member and thus is not concentrated at theconductive pattern members, the electrical connection component has thebending resistance that is twice or more the conventional FPC and theparticular processing for the bending becomes unnecessary.

1. An electrical connection component comprising a plurality ofplate-like flexible conductive pattern members, a sheet-like gel memberhaving said conductive pattern members embedded therein, flexible basematerial sheets retaining said gel member therebetween, a thin filmconductive layer coating an external surface of each of said conductivepattern members, and an additional flexible base material sheetbisecting said gel member in a thickness direction of said gel memberinto two gel portions, said conductive pattern members being disposed insaid gel portions, respectively.
 2. An electrical connection componentaccording to claim 1 wherein said thin film conductive layer is a metalplating layer having a conductivity greater than that of said conductivepattern member.
 3. An electrical connection component comprising aplurality of plate-like flexible conductive pattern members, asheet-like gel member having said conductive pattern members embeddedtherein, and flexible base material sheets retaining said gel membertherebetween, said conductive pattern members being disposed on bothsides of a neutral line which bisects said gel member in a thicknessdirection of said gel member, said conductive pattern members beingdisplaced from one another between said both sides in a direction ofsaid neutral line.
 4. An electrical connection component according toclaim 3, comprising a plurality of thin film conductive layers coatingexternal surfaces of said conductive pattern members.
 5. An electricalconnection component according to claim 4, wherein each of said thinfilm conductive layers is a metal plating layer having a conductivitygreater than that of said conductive pattern member.
 6. An electricalconnection comprising a plurality of plate-like flexible conductivepattern members, a sheet-like gel member having said conductive patternmembers embedded therein, and flexible base material sheets retainingsaid gel member therebetween, said conductive pattern members beingdisposed on a neutral line bisecting said gel member in a thicknessdirection of said gel member, each of said conductive pattern membersbeing oriented obliquely to the neutral line.
 7. An electricalconnection component according to claim 6, wherein a respective thinfilm conductive layer is coated over an external surface of each of saidconductive pattern members and said thin film conductive layer is ametal plating layer having a conductivity greater than that of saidconductive pattern member.